Synthesis and characterization of copolymers of limonene with styrene initiated by azobisisobutyronitrile

Abstract

The radical copolymerization of limonene with styrene by azobisisobutyronitrile in xylene at 80 ± 0.1 °C for 2 h, under inert atmosphere of N 2, yields alternating copolymers. The kinetic expression is R p∝[I] 0.5[Sty] 1.0[Lim] −1.0. The overall activation energy is calculated as 41 kJ/mol. The FTIR and 1H-NMR spectra of copolymers show bands at 3000 and 1715 cm −1 and peaks at 6.8 δ and 5.3 δ due to phenyl protons of styrene and trisubstituted olefinic protons of limonene, respectively. The values of reactivity ratios r 1(Sty)=0.0625 and r 2(Lim)=0.014, calculated by Kelen–Tüdos method. The Alfrey–Price Q– e parameters for limonene are 0.438 and −0.748, respectively. The penultimate unit effect is favoured in the present system and the value of φ is 38.49.